Suppose a student wants to determine the color change interval of an unknown indicator. Her results are given in the table. Tube # pH Unknown indicator 4 6.39 red 5 7.11 red 7.87 purple 7 8.81 purple 8 9.07 blue 9. 10.10 blue What is the interval of the unknown indicator? The color change interval is between pH 7.11 and pH 7.87. The color change interval is between pH 7.11 and pH 9.07. The color change interval is between pH 9.07 and pH 10.10. The color change interval is between pH 6.39 and pH 10.10.

Suppose a student wants to determine the color change interval of an unknown indicator. Her results are given in the table. Tube # pH Unknown indicator 4 6.39 red 5 7.11 red 7.87 purple 7 8.81 purple 8 9.07 blue 9. 10.10 blue What is the interval of the unknown indicator? The color change interval is between pH 7.11 and pH 7.87. The color change interval is between pH 7.11 and pH 9.07. The color change interval is between pH 9.07 and pH 10.10. The color change interval is between pH 6.39 and pH 10.10.

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter15: Acid-base Equilibria

Section: Chapter Questions

Problem 9RQ: What is an acidbase indicator? Define the equivalence (stoichiometric) point and the end point of a...

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A solution has a pH of 4.5. What would be the color of the solution if each of the following indicators were added? (See Fig. 14-8.) a. methyl orange b. alizarin c. bromcresol green d. phenolphthalein
A solution has a pH of 7.0. What would be the color of the solution if each of the following indicators were added? (See Fig. 14-8.) a. thymol blue b. bromthymol blue c. methyl red d. crystal violet
Methyl orange, HMO, is a common acid-base indicator. In solution it ionizes according to the equation: HMOaqH+aq+MO-aqredyellow If methyl orange is added to distilled water, the solution turns yellow. If 1 drop or two of 6 M HCl is added to the yellow solution, it turns red. If to that solution one adds a few drops of 6 M NaOH, the color reverts to yellow. a. Why does adding 6 M HCl to the yellow solution of methyl orange tend to cause the color to change to red? Note that in solution HCl exists as H+ and Cl- ions. b. Why does adding 6 M NaOH to the red solution tend to make it turn back to yellow? Note that in solution NaOH exists as Na+ and OH- ions. How does increasing OH- shift Reaction 3 in the discussion section? How would the resulting change in H+ affect the dissociation reaction of HMO?
. Write the formulas for three combinations of weak acid and salt that would act as buffered solutions. For each of your combinations, write chemical equations showing how the components of the buffered solution would consume added acid and base.
When might a pH meter be better than an indicator to determine the end point of an acid-base titration?
For the following, mix equal volumes of one solution from Group I with one solution from Group II to achieve the indicated pH. Calculate the pH of each solution. Group I: 0.20 M NH4Cl, 0.20 M HCl, 0.20 M C6H5NH3Cl, 0.20 M (C2H5)3NHCl Group II: 0.20 M KOI, 0.20 M NaCN, 0.20 M KOCl, 0.20 M NaNO2 a. the solution with the lowest pH b. the solution with the highest pH c. the solution with the pH closest to 7.00
Two samples of 1.00 M HCl of equivalent volumes are prepared. One sample is titrated to the equivalence point with a 1.00 M solution of sodium hydroxide, while the other sample is titrated to the equivalence point with a 1.00 M solution of calcium hydroxide. a Compare the volumes of sodium hydroxide and calcium hydroxide required to reach the equivalence point for each titration. b Determine the pH of each solution halfway to the equivalence point. c Determine the pH of each solution at the equivalence point.
A solution of weak base is titrated to the equivalence point with a strong acid. Which one of the following statements is most likely to be correct? a The pH of the solution at the equivalence point is 7.0. b The pH of the solution is greater than 13.0. c The pH of the solution is less than 2.0. d The pH of the solution is between 2.0 and 7.0. e The pH of the solution is between 7.0 and 13.0. The reason that best supports my choosing the answer above is a Whenever a solution is titrated with a strong acid, the solution will be very acidic. b Because the solution contains a weak base and the acid (titrant) is used up at the equivalence point, the solution will be basic. c Because the solution contains the conjugate acid of the weak base at the equivalence point, the solution will be acidic.
A solution is prepared from 0.150 mol of formic acid and enough water to make 0.425 L of solution. a Determine the concentrations of H3O+ and HCOO in this solution. b Determine the H3O+ concentration that would be necessary to decrease the HCOO concentration above by a factor of 10. How many milliliters of 2.00 M HCl would be required to produce this solution? Consider that the solution was made by combining the HCl, the HCOOH, and enough water to make 0.425 L of solution. c Qualitatively, how can you account for the differences in the percentage dissociation of formic acid in parts a and b of this problem?
Aluminum chloride, AlCl3, behaves more as a molecular compound than an ionic one. This is illustrated in its ability to form a fourth covalent bond with a chloride ion: AlCl3+ClAlCl4. From the Lewis diagram of the aluminum chloride molecule and the electron configuration of the chloride ion, show that this is an acidbase reaction in the Lewis sense, and identify the Lewis acid and the Lewis base. Aluminum chloride is a white solid at room conditions, although it is typically manufactured mixed with some yellow ironIII chloride. Its appearance is that of an ionic compound.
A solution is made by dissolving 15.0 g sodium hydroxide in approximately 450 mL water. The solution becomes quite warm, but after it is allowed to return to room temperature, water is added to bring the volume to 500.0 mL of solution. (a) Calculate the pH and pOH in the final solution. (b) Why would we wait for it to return to room temperature? (c) If the mass of the water used to initially dissolve the sodium hydroxide were exactly 450 g and the temperature of the water increased by 8.865 C, how much heat was given off by the dissolution of 15.0 g of solute? Assume the specific heat of the solution is 4.184 J/g. K. What is the molar heat change for the dissolution of sodium hydroxide (known as the enthalpy of solution, Hsol)?
What is an acidbase indicator? Define the equivalence (stoichiometric) point and the end point of a titration. Why should you choose an indicator so that the two points coincide? Do the pH values of the two points have to be within 0.01 pH unit of each other? Explain.